Sound problems under Debian

Hello
I've just succeeded to install Debian on the Freerunner together with
xfce4 following the instructions in
<http://wiki.debian.org/DebianOnFreeRunner> and
<http://wiki.openmoko.org/wiki/Debian>.
Most things run fine and just as expected.
There are, however, sound problems. The Wiki doesn't give any special
instruction on sound, like installing a new alsa-package or building a
kernel module. Can I have overlooked anything?
1. There seems to be no sound at all. 'aplay file.wav' just pretends
to play but neither gives any output nor returns the cursor.
2. xfmedia doesn't start at all. An attempt to start the program from
a shell, too, doesn't give any output or error message.
3. The ring tone is just a lousy noise.
4. During a phone call, voices are poorly transmitted (noisy), for me
as well as for the recipient.
Help would be very welcome. Everything is working alright under the
default system. So, a hardware defect can be excluded.
Thanks
Sven
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